There are many applications in academic, industrial, and medical fields, as well as others, that may benefit from devices and methods that are capable of accurately and controllably delivering fluids, including liquids and gases that have a beneficial effect when administered in known and controlled quantities. Such devices and methods may be particularly useful in the medical field where much of the treatments for a large percentage of patients includes the administration of a known amount of a substance at predetermined intervals.
Insulin-injecting pumps have been developed for the administration of insulin for those suffering from both type I and II diabetes. Recently continuous subcutaneous insulin injection and/or infusion therapy has been adapted for the treatment of diabetes. Such therapy may include the regular and/or continuous injection or infusion of insulin into or under the skin of a person suffering from diabetes and offers an alternative to multiple daily injections of insulin by an insulin syringe or an insulin pen.
Generally, present insulin pump therapy is based on the use and application of currently available, so-called, “rapid-acting” insulin analogues, including insulin lispro (marketed by Eli Lily & Company under the trademark Humalog®), insulin glulisine (marketed by Sanofi-Aventis under the trademark Apidra), and insulin aspart (marketed by Novo Nordisk under the trademark NovoLog). More recently, ultra-rapid acting insulins have been developed. Further, other drugs have been developed that either modify insulin action time or alter the rate of metabolism of food. These all change the way that post-prandial blood glucose levels behave in a somewhat similar fashion.
Currently, in presently available insulin pumps, an insulin bolus is delivered as rapidly as it can be. The delivery of an insulin bolus creates an abrupt rise in the level of insulin in the blood stream which encourages the rapid metabolism of glucose. The beginning of insulin appearance in the blood stream is delayed from the time of infusion because of the time required for insulin absorption and distribution in the circulation. With ultra-rapid acting insulins the delay time is less than for fast acting insulin. Thus, the delivery of such an insulin bolus according to a “normal” protocol may cause an excessive metabolism of glucose thereby causing a drop in blood glucose which can be dangerous. In extreme cases, the drop in blood glucose can lead to insulin shock, which is also known as hypoglycemic shock. In rare cases hypoglycemic shock can even cause death.
The use of pramlintide, (e.g., pramlintide acetate marketed by Bristol Myers-Squibb under the trademark Symlin) is becoming increasingly common in the treatment of type I diabetes. Pramlintide is synthetic amylin, an agent that acts to slow the rate of gastric emptying and therefore the rate at which food is released into the small intestine. Accordingly, this slows the rate at which food is metabolized. Glucagon-like peptide-1 (GLP-1) agonist therapy may also be used to slow the rate of gastric emptying which in turn slows the rate of absorption of food in the small intestine. The use of these agents results in a less pronounced rise in blood sugar after eating that also may last for a longer period of time.
The development of new insulins as well as adjunctive medicinal therapy for diabetes creates a need for new therapy protocols to be used with an insulin pump or a dual therapy insulin pump.